finer mesh giving poorer steady state results

  • Last Post 14 February 2020
Wasif posted this 11 February 2020

In the global settings, I changed the relevance center and span angle to fine. It is giving me good results.

However, when I use sphere of influence at point of contact to reduce the element size for h-adaptivity, I get poorer results.

Does someone know why?

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rwoolhou posted this 11 February 2020

Define poorer. 

Wasif posted this 11 February 2020

Experimental Data Shows that temperature should be 57degrees at a certain point. I am also getting around 57 using a coarse mesh but getting around 47 using a fine mesh.

peteroznewman posted this 12 February 2020

Two wrongs don't make a right. 

Smaller elements are going to provide better simulation accuracy, or point out the presence of a singularity in the model. If the temperature keeps increasing with each reduction in element size, then that is evidence of a singularity in the model and you have to fix that before you can use the maximum temperature in the model as a useful output.

If there is no singularity, then other boundary conditions or material properties are incorrect and don't represent the experimental conditions accurately. Those have to be changed to get better agreement with the experimental result.

Wasif posted this 13 February 2020

I agree with what you said. However, when I try to fine the mesh from the global settings, the results are well within the experimental range. It is only when I add mesh refinement in addition to the global settings.

peteroznewman posted this 14 February 2020

You will have to provide a lot more detail if you want to understand why adding a mesh refinement makes the solution shift so much. You will have to insert images into your reply showing the mesh and the initial results, then the mesh refinement and the changed results.